Homology refers to similar structures with dissimilar functions, but with similar origin and architecture.
Examples of Homologous Structures:
Forelimbs: The forelimbs of higher vertebrates are examples of homologous organs. The forelimbs of a bird, whale, cat, a horse, a bat, mole, a monkey and man are doing different functions; but they have similar anatomy in all the animals.
Brains: Brain of vertebrates, from fishes to mammals, are constructed in the same pattern. In all these animals the brain is formed of olfactory lobes, olfactory peduncle, pituitary gland, optic lobes, cerebrum, cerebellum, medulla etc.
Heart: In fishes, the heart is formed of two chambers, namely auricle, and a ventricle. Amphibians have three chambers, namely two auricles and a ventricle. In some reptiles (turtles) the ventricle is partly divided so that theoretically there are three and a half chamber.